No getting to the boss is the best way to get engrams. If you have done the nightfall you get 31 rep from the 24 strikes. Now I always seem to get 2 decoherent engrams when the timer starts. Do these strikes 10 times and you can level up the crypts rich and that is only if you don't find any other engrams. That is like a chance at a legendary every three or four hours if your fast 250-310 rep and 50 marks..